You are familiar with the term catfishing, people adopting false identities to gain trust, love and money. Tonight a year-long "nightline" vestigation follows a trail of deceit. Often celebrities including mu music award brad paisley and his wife. For a chance to help, seemed like a beautiful gift. Until it all turned out to be an ugly lie. Here's abc's david wright. Wow, I want to be him. Reporter: You cut write a country song about online relationships. In fact, brad paisley did. &#9834; &#9834; his number one single online. In the music video, george castanza, jason alexander plays a nerd who passes himself on line as ultracool paisley. &#9834; Online in hollywood, I'm 6'5" &#9834; &#9834; &#9834; it is the idea of the fantasy world that the internet has become. Reporter: You have experienced the dark side of that. Yeah, the dark side has been there. Reporter: Brad and his wife, kimberly williams-paisley had no idea how dark it could get until they were sucked into a cruel, elaborate hoax, a hoax that left kim paralyzed with fear. I felt so violated. And scared. Reporter: Brad demanding justice. Sort of like emotional terrorism. Reporter: It started with an e-mail sent by a tee te-mail sent by a stranger, this one stood out, a mother with her daughter's dying wish. 8 years old, had cancer, had seen a movie called "the christmas shoes" and said her daughter had found great hope and inspiration from this movie. Always know that I am going to be here. She said her daughter begged her to get in touch with me. It sounded very sort of real. I read that. I thought, I would love to just talk to her. Say hi. Reporter: Talk they did. By phone, e-mail and text. I heard this rustling. She put this little girl on the phone. Said this is claire. I just wanted to say thank you for letting me love you. And thank you for being my miracle. I remember this, this instinct in me, thinking what if this is a hoax? But it was so quickly trumped by an overwhelming feeling, what if it is not a hoax. And I have a chance to help this little girl. Reporter: The paisleys were in good company. A lot of people thought it was real. For the past year, "nightline" has been piecing together evidence from other celeb ri teamri -- celebrities. E-mail to the patz yslies. Here is another one written to, gospel singer, carmen hope thomas. It is the same thing written to, natalie grant,singer. Reporter: The producer is still finding victims. We confirmed at least a dozen people. There are at least a dozen more working to confirm still. Reporter: Who is in your collection? John henson, host of wipeout. Band, little big town. Kate goeslin. In loving memory of hope. Kate goeslin, we told her it was a hoax. Rip s Reporter: She learned from us? When I received your e-mail. I yelled out loud. Oh, my gosh. Reporter: At this point the paisleys were hooked. It was plausible? Totally plausible to me. They weren't saying can you send money. They weren't saying can you come visit. They were saying we just, I want to talk to you. Reporter: And then -- it started to get weird. &#9834; Jesus loves me this I know &#9834; Reporter: Supposedly at death's door the little girl sang this song for kim. And brad got on the phone. And sang to her. Amazing grace. Your's singing to some one's dying kid. There is no way that is not real. How can that not be real. Reporter: Right when they're hooked the hammer drops. They get the call they're drthey're dregd. Little claire its dead. The call came. Very to the point. She said she is gone. A parent's worst nightmare. My wife started bawling. She lit my softest spot. As a mother. Wanting my kids to be okay. Hi, it is just carrey. Reporter: The calls continued. Got more outlandish. I also wanted to know if there is a version of your husband singing amazing grace, that I could use that for the service. Reporter: Check out the message. Detailing plans for the funeral. Oh, it was okay to put your picture in the casket, like she reap quested. Hope you have a good weekend. And thank you for everything. Bye-bye. Reporter: Almost immediately the story started to unravel. I said where can I send flowers for the funeral. Reporter: She don't have an address? Don't. Send a donation to your local children's hospital. I had like a physical reaction. Every red flag went up. I remember just looking at people, around me, who is it? How many people were involved in this scam? And, and are they, are they right here? Are they watching me right now? You were worried they might be a threat to you? Yes, this person was crazy. I watched my wife buckle when she realized thisn wasn't a real girl. I vowed I will find her. I will make sure this person is not able to do this. Or isn't capable of doing worse. Reporter: This deception was bigger than the paisleys imagined. As "nightline" dug deeper it became clear the hoaxer wasn't just stalking celebrities she was stalking cancer victims stealing photos and stories. We want to meet one family, the thomases of ohio. Their daughter christie died in 2006 of guess what, neuroblastoma. Scammers stole her image off the thomas family's memorial website. I had one of the detectives tell me, a while ago the was almost like, she knew my story, better than I knew my story. She had red my journal entry so many times it was like she internalized it. She would be calling famous people it was like she convinced herself she really was me. That is the sickest part about this. That is the part when I start to talk about that. That's when I get really mad. That there were real kids. That there were real photos. Reporter: Ironically the photos helped unravel the mystery. You pulled the data off some of these pictures. These journal entries were in some ways her undoing. She created them. Didn't lift them. Reporter: Buried in digital images location data from the camera they were taken on. When you enter it in google maps it shows a location in mongolia. Reporter: Dead end at first. Simply mongolia is on the opposite side of the world. If you enter a negative sign here, you get the actual address. 206 walnut street. Wow. In douglas, wyoming, hometown of jackalope, a mythical creature to fool city shrekkers. Fitting location for a hideout. We found her at a k 08 campground. Finally after eight months of searching for the woman responsible for toying with so many people's emotions. We are face to face with her. Hope jackson. 37-year-old mother of two perfectly healthy kids. You never god forbid had the experience of losing a child? No. No. I hope I never do, yeah. Reporter: You don't think it was incredibly bad karma? Yes, yes. Yeah. Well, now looking back on it, of course. Yeah. Reporter: We spent a whole day with her. She was contrite. I am 100% responsible for this. I have to live with that every day of my life. Philosophical. I hope it brings healing not only for the people it hurt but me. Reporter: Showed flashes of anger. All I can do is a poll jpologize. Broke down in tears again and again. Horrible. Shameful. I hurt. Wrong. Reporter: We confronted her with an e-mail she wrote angela thomas. Promising to stop using christie's picture. I hope to learn to become a better person, mother. I don't expect forgiveness. How sorry I am. I will not use your photos ever again. Or any one else's. Thank you for your time. Reporter: You sent that? Uh-huh. Reporter: It was after you sent that that you first contacted kim and brad? Right. Reporter: After saying to this woman. I will not be using your photos ever again. And I never, I didn't use her photos ever again. Reporter: Or anyone else's. Uh-huh. Reporter: If you lied to her, why should we believe you snow. I'm not asking you to believe me. Because like I said it is my actions are going to speak louder than my word are. Reporter: She insists for her it was never about gift or money. I never asked for anything from them. Reporter: Does it matter she doesn't ask for money? Yeah, I think that's secce sicker. I would have welcomed the thought this was something as simple as a woman, scamming you. Then it's look okay. At least money is involved. When sthep whe was all along careful not to do that, you realize she is just, enjoying this. Reporter: It may be morally wring to fool someone on line, but not necessarily illegal. She hadn't typically commit aid crime because she didn't ask for money. And she, that shows you what a pro she was. Reporter: Turned out hope jackson made one little mistake that finally caught up with her. Let's figure out which laws she broke. She has to have broken something. Reporter: What was her mistake? What were the consequences?

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